/**
 * @author richardmattka / http://embarkinteractive.com/
 *
 * Custom RGB Opacity Shift Shader
 * Shifts red and blue channels from center in opposite directions
 * Also uses opacity 
 * Based on Shader from Felix Turner 
 * Originally Ported from http://kriss.cx/tom/2009/05/rgb-shift/
 * by Tom Butterworth / http://kriss.cx/tom/
 *
 * amount: shift distance (1 is width of input)
 * angle: shift angle in radians
 */

THREE.IDRGBShiftShader = {

	uniforms: {
		"tDiffuse": { type: "t", value: null },
		"amount":   { type: "f", value: 0.05 },
		"angle":    { type: "f", value: 0.0 },
		"opacity":    { type: "f", value: 0.5 }

	},

	vertexShader: [

		"varying vec2 vUv;",

		"void main() {",

			"vUv = uv;",
			"gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",

		"}"

	].join( "\n" ),

	fragmentShader: [

		"uniform sampler2D tDiffuse;",
		"uniform float amount;",
		"uniform float angle;",
		"uniform float opacity;",

		"varying vec2 vUv;",

		"void main() {",

			"vec2 offset = amount * vec2( cos(angle), sin(angle));",
			"vec4 cr = texture2D(tDiffuse, vUv + offset);",
			"vec4 cga = texture2D(tDiffuse, vUv);",
			"vec4 cb = texture2D(tDiffuse, vUv - offset);",
			"gl_FragColor = vec4(cr.r, cga.g, cb.b, opacity);",

		"}"

	].join( "\n" )

};
